UDOT outlines overnight demolition, detours for Riverdale bridge replacements; city warned of temporary emergency-access limits

UDOT project staff and consultant Horrocks briefed the Riverdale City Council on Aug. 5 on an accelerated plan to replace three bridges in the 4400 South corridor that the agencies said are structurally due for replacement.

Aubrey Benyon, UDOT's public outreach manager for the project, told the council construction work will begin Aug. 11 and that demolition of the 4400 South bridge over I-15 is scheduled overnight Aug. 22 into Aug. 23. "This bridge is coming down in one swoop," Benyon said, describing a protected, overnight demolition window designed to reduce overall risk and shorten the schedule.

Benyon and Kevin Griffin, the Horrocks field engineer on the job, said the contractor proposed a full closure for the demolition and follow-on work. They described signed detours routing northbound traffic via the Riverdale Road off-ramp and I-84 ramps, and southbound traffic via the I-84 flyover and loop ramp to re-enter I-15. UTA Route 640 stops in the immediate limits will be suspended and bus service redirected while the closures are in place.

UDOT officials emphasized pedestrian access will be maintained: the pedestrian overpass over I-15 will remain in place throughout construction so people can still walk along 4400 South. Benyon said the demolition technique and weekend bridge slides for other structures should shorten construction from an anticipated 18 months to roughly 10–11 months and produce about $500,000 in cost savings.

Council members pressed staff on emergency vehicle access. Benyon acknowledged that while emergency access can be accommodated during the larger closure period, there may be overnight windows when no crew is available to move barriers: "There will be times that there will be nobody there to move the barrels," she said, recommending coordination with neighboring Roy for west-side responses and assuring the city that emergency needs will be handled case by case.

City staff and UDOT also outlined public outreach efforts: weekly email updates, a hotline and a project webpage, mailed postcards announcing a contractor open house, and options to share maps and graphics through municipal newsletters and social media. UDOT said the 4400 South section between Airport Road and Parker Drive will close for about six weeks while the contractor builds bridge walls; the 4400 S. span over I-15 is expected to remain closed longer, with full corridor work into the fall and bridge decks set to be slid into place during short weekend operations.

The council did not take formal action on the presentation. Mayor (unnamed) thanked the presenters and asked staff to keep contact information readily available for the council and residents.